Magnetic head wherein one of multiple insulating layers determines a zero throat level position

ABSTRACT

A magnetic head comprises: an induction type head for recording including a lower magnetic core, a writing gap film formed on the lower magnetic core, an upper magnetic core having a track portion and a portion spreading from the track portion, a plurality of insulating films laminated between the lower magnetic core and the upper magnetic core, and a coil formed between the plurality of insulating films. One of the plurality of insulating films is an insulating film determining a zero throat level position. The track portion of the upper magnetic core extends to an air bearing surface. A magnetoresistance effect type head for reproducing includes a lower shielding film and a magnetoresistance effect sensor film between the lower shielding film and the lower magnetic core. The position where the upper magnetic core spreads is located nearer to the air bearing surface than the tip end position arranged nearest to the air bearing surface among the tip end positions of the insulating films formed on the insulating film determining the zero throat level position. This can provide a magnetic head having good magnetic characteristics and improved accuracy in the width of a track on the air bearing surface.

This is a continuation application of U.S. Ser. No. 09/343,724 filedJun. 30, 1999, now U.S. Pat. No. 6,436,560.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic head of the type having arecording head and a reproducing head separately and used for a magneticrecording/reproducing device and a magnetic disc device using themagnetic head.

2. Description of the Related Art

One of the magnetic heads of the type having a recording head and areproducing head separately is a magnetic head using a magnetoresistanceeffect element (hereinafter referred to as “MR element”). The MR elementuses the characteristics that resistance changes in response to a changein the intensity of magnetic field and its reproducing output does notdepend on the running speed of a magnetic recording medium, but dependsonly on the amount of magnetic flux of a magnetic signal. Therefore, theMR element can produce a sufficient reproducing output even if therunning speed is low and hence has an advantage in increasing therecording density of a magnetic recording device and in reducing thesize thereof.

The magnetic head of this kind is disclosed in IEEE Transaction onMagnetics, Vol. 26, page 1689, 1990, for example.

The magnetic head has increased the number of turns of coil in order towrite by an intense magnetic field and to produce a large reproducingoutput and an insulating film for insulating the coil has been formed inmultiple layers. Japanese Unexamined Patent Publication No. Hei 3-156714discloses a technology for covering the whole multiple insulating filmsby the other insulating film in order to eliminate a level differenceproduced by the multiple insulating films.

On the other hand, in order to improve the areal recording density ofmagnetic recording, it will be necessary in the future to extensivelyincrease a track density as well as a linear recording density. Thisrequires that the track of a magnetoresistance effect head (hereinafterreferred to as “MR head”) be formed in still narrower width and withhigher accuracy.

The conventional magnetic head described above is not sufficient in theaccuracy of a zero throat level position because it has the otherinsulating film covering the whole multiple insulating films forinsulating the coil. In this connection, a throat level portion means aportion from the air bearing surface of a magnetic core to the tip endof interlayer insulating films for vertically separating an uppermagnetic core from a lower magnetic core more than the thickness of awrite gap. A zero throat level position means the tip end position ofthe insulating film nearest to the air bearing surface of the magneticcore among the interlayer insulating films.

On the other hand, the structure having no other insulating filmcovering the whole insulating films for insulating the coil has thefollowing problem. The upper magnetic core is formed by a methodcomprising the steps of forming an underlying layer for plating on theinsulating film for insulating the coil, forming a frame thereon by aphotoresist, and electroplating the space thereof with a conductivefilm. However, when a frame pattern is formed, the light from a patternexposure system is reflected by the underlying layer for plating at thelevel difference portion of the insulating film to produce halation. Thephotoresist of the unnecessary portion is exposed to the light.Therefore, for example, there exists a problem that a part of themagnetic core forming a track is not formed in a desired shape and thatthe accuracy of a track width is not sufficient.

Next, the conventional magnetic head will be described with reference todrawings. FIG. 1A is a plan view of an upper magnetic core and FIG. 1Bis a cross sectional view showing a part of the magnetic head. In FIG.1B, a first layer insulating film 7 is formed on a write gap film 20 anda second layer insulating film 9 a for protecting a coil 8 is formedthereon and a third layer insulating film 9 b for protecting the coil 8is formed thereon and further an upper magnetic core 10 is formedthereon via an underlying layer 25 for plating.

The upper magnetic core 10 is formed by the use of a pattern formed froma positive photoresist (not shown) on the underlying layer 25 forplating formed on the third layer insulating film 9 b formed on thesecond layer insulating film 9 a formed on the first layer insulatingfilm 7.

As shown in FIG. 1A, if the position Pa where the upper magnetic core 10spreads is located on the level difference portion of the second layerinsulating film 9 a or to the right hand side in the drawing, that is,in the direction away from the air bearing surface 36, a depression isproduced in the side of the resist pattern of the track portion 10 a (inFIG. 1A, a left portion from the position Pa where the upper magneticcore spreads) by the reflecting light from the underlying film 25 forplating to produce a spreading portion 10 b at the track portion 10 a ofthe upper magnetic core 10, when the photoresist is exposed to thelight.

In the structure like this, since the portion where the magnetic flux ofthe upper track is to be contracted is expanded, the magneticcharacteristics deteriorate. Further, when the air bearing surface isformed, if the track portion corresponding to the air bearing surface isexpanded, there are produced variations in the width of the track of theair bearing surface 36.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a magnetic headhaving good magnetic characteristics and improved accuracy in the widthof a track on an air bearing surface.

It is another object of the present invention to provide a magnetic discdevice using the magnetic head like this.

In order to achieve the object, the magnetic head in accordance with thepresent invention comprises a magnetoresistance effect type head forreproducing and an induction type head for recording and has two or moreinterlayer insulating films vertically separating an upper magnetic corefrom a lower magnetic core more than the thickness of a write gap. Theposition where the upper magnetic core spreads from a track portion islocated nearer to an air bearing surface than the tip end positionnearest to the air bearing surface among the tip end positions of theinsulating films which are formed on the insulating film determining thezero throat level position and have level differences to each other.

If the insulating film which is formed on the insulating filmdetermining the zero throat level position and has a level difference isone layer, it is essential only that the position where the uppermagnetic core spreads from the track portion is located in front of (tothe air bearing surface side of) the tip end position, that is, the tipposition of the level difference, of the insulating film. If two or moreinsulating films with a level difference to each other are arranged, itis required only that the position where the upper magnetic core spreadsfrom the track portion should be located in front of the tip endposition of the insulating film whose tip end position is nearest to theair bearing surface.

The position where the upper magnetic core spreads may be located on theinsulating film determining the zero throat level or nearer to the airbearing surface side, that is, directly on the write gap film. However,it is desirable that it is located about 0.5 μm or more behind the airbearing surface, that is, to the zero throat level side.

Further, in order to achieve the second object of the present invention,the magnetic disc device in accordance with the present inventioncomprises a rotatable magnetic recording medium having an informationrecording layer, a drive motor for rotating the magnetic recordingmedium at high speeds, a control means for controlling the rotation ofthe drive motor, a magnetic head provided with an electromagneticconverter for writing or reading information into or from the recordinglayer and movable on the recording layer of the magnetic recordingmedium. The magnetic head is used as this magnetic head, a circuit meansfor controlling the information by which the magnetic head write or readthe information, a positioning means for positioning the magnetic headat a predetermined position on the magnetic recording medium at highspeeds, and a control circuit for controlling the positioning means.

In order to achieve the object of the present invention, the magnetichead in accordance with the present invention comprises: an inductiontype head for recording including a lower magnetic core, a write gapfilm formed on the lower magnetic core, an upper magnetic core having atrack portion and a portion spreading from the track portion, aplurality of insulating films laminated between the lower magnetic coreand the upper magnetic core, and a coil formed between the plurality ofinsulating films. One of the plurality of insulating films is aninsulating film determining a zero throat level position. The trackportion of the upper magnetic core is an air bearing surface.

The magnetic head further comprises a magnetoresistance effect type headfor reproducing including a lower shielding film and a magnetoresistanceeffect sensor film formed between the lower shielding film and the lowermagnetic core. The position where the upper magnetic core spreads islocated nearer to the air bearing surface than the tip end positionarranged nearest to the air bearing surface among the tip end positionsof the insulating films formed on the insulating film determining thezero throat level position.

In the magnetic head, in the case where the plurality of insulatingfilms comprise a first insulating film and a second insulating film andthe first insulating film is the insulating film determining the zerothroat level position. When the second insulating film is formed on thefirst insulating film, the position where the upper magnetic corespreads is located between the tip end of the second insulating film andthe air bearing surface.

Further, in the magnetic head, in the case where the plurality ofinsulating films comprise a first insulating film, a second insulatingfilm and a third insulating film and the first insulating film is theinsulating film determining the zero throat level position and thesecond insulating film is formed on the first insulating film and thethird layer insulating film is formed on the second layer insulatingfilm and the tip end position of the second insulating film is locatednearer to the air bearing surface than the tip end position of the thirdinsulating film, the position where the upper magnetic core spreads islocated between the tip end of the second insulating film and the airbearing surface.

Still further, in the magnetic head, in the case where the plurality ofinsulating films comprise a first insulating film, a second insulatingfilm and a third insulating film and the second insulating film formedon the first insulating film is the insulating film determining the zerothroat level position and the third insulating film is formed on thesecond insulating film, the position where the upper magnetic corespreads is located between the tip end of the third insulating film andthe air bearing surface.

Furthermore, in the magnetic head, in the case where the plurality ofinsulating films comprise a first insulating film and a secondinsulating film. The second insulating film formed on the firstinsulating film is the insulating film determining the zero throat levelposition, the position where the upper magnetic core spreads is locatednearer to the air bearing surface side than the zero throat levelposition.

In order to achieve the object of the present invention, a magnetic discdevice in accordance with the present invention comprises: a rotatablemagnetic recording medium having an information recording layer; a drivemotor for rotating the magnetic recording medium at high speeds; and amagnetic head movable on the recording layer of the magnetic recordingmedium in order to write or read the information into or from therecording layer. The magnetic head comprises: an induction type head forrecording including a lower magnetic core, a write gap film formed onthe lower magnetic core, an upper magnetic core having a track portionand a portion spreading from the track portion, a plurality ofinsulating films laminated between the lower magnetic core and the uppermagnetic core, and a coil formed between the plurality of insulatingfilms. One of the plurality of insulating films being an insulating filmdetermining the zero throat level position and the tip end of the trackportion of the upper magnetic core being the air bearing surface. Themagnetic device further comprises a magnetoresistance effect head forreproducing including a lower shielding film and a magnetoresistanceeffect sensor film formed between the lower shielding film and the lowermagnetic core. The position where the upper magnetic core spreads islocated nearer to the air bearing surface than the tip end positionarranged nearest to the air bearing surface among the tip end positionsof the insulating films formed on the insulating film determining thezero throat level position.

In the magnetic disc device, in the case where the plurality ofinsulating films comprise a first insulating film and a secondinsulating film and the first insulating film is the insulating filmdetermining the zero throat level position and the second insulatingfilm is formed on the first insulating film, the position where theupper magnetic core spreads is located between the tip end of the secondinsulating film and the air bearing surface.

Further, in the magnetic disc device, in the case where the plurality ofinsulating films comprise a first insulating film, a second insulatingfilm and a third insulating film and the first insulating film is theinsulating film determining the zero throat level position and thesecond insulating film is formed on the first insulating film and thethird insulating film is formed on the second insulating film and thetip end position of the second insulating film is located nearer to theair bearing surface than the tip end position of the third insulatingfilm, the position where the upper magnetic core spreads is locatedbetween the tip end of the second insulating film and the air bearingsurface.

Still further, in the magnetic disc device, in the case where theplurality of insulating films comprise a first insulating film, a secondinsulating film and a third insulating film and the second insulatingfilm formed on the first insulating film is the insulating filmdetermining the zero throat level position and the third insulating filmis formed on the second insulating film, the position where the uppermagnetic core spreads is located between the tip end of the thirdinsulating film and the air bearing surface.

Furthermore, in the magnetic disc device, in the case where theplurality of insulating films comprise a first insulating film and asecond insulating film and the second insulating film formed on thefirst insulating film is the insulating film determining the zero throatlevel position, the position where the upper magnetic core spreads islocated nearer to the air bearing surface side than the zero throatlevel position.

In order to achieve the object of the present invention, a magnetic discdevice in accordance with the present invention comprises: a rotatablemagnetic recording medium having an information recording layer; a drivemotor for rotating the magnetic recording medium at high speeds; acontrol means for controlling the rotation of the drive motor; amagnetic head provided with an electromagnetic converter for writing orreading the information into or from the recording layer and movable onthe recording layer of the magnetic recording medium; a circuit meansfor controlling the information by which the magnetic head writes orreads the information into or from the magnetic recording medium; apositioning means for positioning the magnetic head at a predeterminedposition on the magnetic recording medium at high speeds; and a controlcircuit for controlling the positioning means. The magnetic head furthercomprises a magnetoresistance effect type head for reproducing and aninduction type head for recording, wherein the tip end of the trackportion of the upper magnetic core of the induction type magnetic headconstitutes the air bearing surface and interlayer insulating filmsvertically separating the upper magnetic core from a lower magnetic coremore than the thickness of a write gap include two or more insulatingfilms and have a coil therebetween. The position where the uppermagnetic core spreads from the track portion is located nearer to theair bearing surface side than the tip end position nearest to the airbearing position among the tip end positions of the insulating filmsformed on the insulating film determining the zero throat level andhaving a level difference to each other.

Further, in the magnetic disc device, the insulating film having a leveldifference is one layer and the position nearest to the air bearingsurface among the tip end positions of the insulating films is the tipend position of the insulating film having the level difference.

These and other objects, features and advantages of the presentinvention will be apparent from the following more particulardescription of the preferred embodiments of the present invention, asillustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plan view of an upper magnetic core and FIG. 1B is a crosssectional view showing a part of a magnetic head.

FIG. 2A is a plan view showing one preferred embodiment of the magnetichead in accordance with the present invention and FIG. 2B is a crosssectional view thereof.

FIG. 3 is a partial cross sectional view in perspective of the magnetichead shown in FIG. 2.

FIG. 4 is a schematic perspective view showing one preferred embodimentof the magnetic disc provided with the magnetic head in accordance withthe present invention.

FIG. 5A is a plan view showing another preferred embodiment of themagnetic head in accordance with the present invention and FIG. 5B is across sectional view thereof.

FIG. 6A is a plan view showing still another preferred embodiment of themagnetic head in accordance with the present invention and FIG. 6B is across sectional view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Magnetic discs in accordance with the present invention and onepreferred embodiment of the magnetic disc device using the magnetic discwill hereinafter be described with reference to the accompanyingdrawings.

FIG. 2A is a plan view showing one preferred embodiment of the magnetichead in accordance with the present invention and FIG. 2B is a crosssectional view thereof. In the drawings, like reference numeralsdesignate like or corresponding components in FIG. 1 and the descriptionthereof will be omitted except for differences in constitution.

As shown in the plan view of the magnetic head shown in FIG. 2A, themagnetic head in accordance with the present invention is provided withan upper magnetic core 10 and insulating films. As is evident from FIG.2B, the insulating films comprises a first layer insulating film 7, asecond layer insulating film 9 a, and a third layer insulating film 9 b.

As is evident from FIG. 2B, the magnetic head comprises a lowershielding film 2, an MR lower gap film 32 made of alumina and formed onthe lower shielding film 2, a magnetoresistance effect sensor film 3formed on the MR lower gap film 32, an MR upper gap film 34 formed onthe magnetoresistance effect sensor film 3 and the MR lower gap film 32,an upper shielding film-cum-lower magnetic core film 6 formed on the MRupper gap film 34, and a write gap film 20 formed on the upper shieldingfilm-cum-lower magnetic core film 6 formed on the MR upper gap film 34.In the present preferred embodiment, a zero throat level position P0 islocated at the tip end of the first layer insulating film 7.

In the present preferred embodiment, a position Pa where the uppermagnetic core 10 shown in FIG. 2A spreads is located on the insulatingfilm determining the zero throat level position P0. In this case, on thefirst layer insulating film 7, and nearer to an air bearing surface 36than the tip end 37 of the second layer insulating film 9 a formedthereon. Therefore, when the photoresist described above is exposed tolight, the periphery of a track portion 10 a is not exposed to the lightreflected by an underlying layer 25 for plating and hence the trackportion 10 a can be formed like a nearly linear structure.

In the magnetic head of the present preferred embodiment, aninduction-type head for recording comprises the upper shieldingfilm-cum-lower magnetic core 6, the write gap film 20, the coil 8, thefirst layer insulating film 7, the second layer insulating film 9 a, thethird layer insulating film 9 b, the underling layer 25 for plating, andthe upper magnetic core. A magnetoresistance effect type head comprisesthe lower shielding film 2, the MR lower gap film 32, the MR upper gapfilm 34, the magnetoresistance effect sensor film 3, the upper shieldingfilm-cum-lower magnetic core film 6.

Next, a process for manufacturing the magnetic head will be describedwith reference to FIG. 3.

FIG. 3 is a partial cross sectional view in perspective of the magnetichead shown in FIG. 2. In the drawing, the lower shielding film 2 formedof a magnetic film made of Permalloy (NiFe) or the like and the lowergap film 32 formed of insulating film made of alumina or the like (notshown in FIG. 3 to avoid making the drawing complex, see FIG. 2B) areformed on a ceramic substrate 1 and the magnetoresistance effect sensorfilm 3 is formed like stripes. The magnetoresistance effect sensor film3 comprises a plurality of films such as magnetoresistance effect filmsusing magnetic material such as Permalloy (NiFe) and bias films forbiasing the magnetoresistance effect films. Further, at the side of themare formed a magnetic domain control film 4 for stabilizing the magneticdomain of the magnetoresistance effect sensor film 3 and an electrodeconductive film 5 for supplying a current for making themagnetoresistance effect sensor film 3 function as a sensor. Theelectrode conductive film 5 is formed by a lift-off method. The uppergap film 34 (not shown, see FIG. 2B) formed of the insulating film madeof alumina or the like are formed on the electrode conductive film 5. Inorder to put the electrode conductive film 5 into contact with a leaderline 12, the desired portion of the upper gap film 34 on the electrodeconductive film 5 is removed to make an aperture. The leader line 12 ofthe electrode conductive film 5 extends outside from the lower shieldingfilm 2. Further, the leader line 12 is simultaneously formed of the samefilm as the upper shielding film-cum-lower magnetic core film 6 and ispatterned in a predetermined shape. This film is formed of the magneticfilm such as Permalloy or the like. Further, the write gap film 20 (notshown, see FIG. 2B) is formed thereon.

Next, as shown in FIG. 2B, the first layer insulating film 7 made ofresist is formed on the write gap film 20. The coil 8 for passing acurrent through the induction-type head is formed on the first layerinsulating film 7 by a plating method and the second layer insulatingfilm 9 a is formed thereon by the same process as used for the firstlayer insulating film 7. Further, the coil 8 and the third layerinsulating film 9 b are formed thereon. In this manner, a multiple-layerstructure is formed as shown in FIG. 2B. Although this multiple-layerstructure is not shown in FIG. 3, it can be understood with reference toFIG. 2B. Then, the upper magnetic core 10 is formed thereon.

The upper magnetic core 10 is formed by the use of a plating film.First, a resist frame for a magnetic plating film is formed on theunderlying layer 25 for plating. At this time, by suitably shaping masksfor forming the insulating films 7, 9 a, 9 b and the resist frame forthe magnetic plating film, as shown in FIGS. 2A, 2B, the position Pawhere the upper magnetic core 10 spreads is located nearer to the airbearing surface 36 than the tip end of the second layer insulating film9 a on the first layer insulating film 7 determining the zero throatlevel.

In this respect, since the above-mentioned upper shieldingfilm-cum-lower magnetic core film 6 is larger in area than theinsulating films 7, 9 a, 9 b, the first layer insulating film 7, thesecond layer insulating film 9 a and the third layer insulating film 9 bcan be formed in a nearly flat plane, whereby defects caused by a breakin a coil can be reduced in number.

Finally, a terminal 11 for connecting a lead wire and a protective filmfor protecting an element are formed. This is the end of the process formanufacturing the magnetic head. In this connection, the same elementsare arranged at equal intervals on a wafer and are manufactured at thesame time and then are divided into individual magnetic heads. Tenwafers were manufactured in accordance with the manufacturing processshown by the preferred embodiment described above and the size of uppertrack of the wafer was measured from the air bearing surface for all theelements. The variation 3 σ in measurements was 0.13 to 0.19 μm.

In order to compare with the magnetic head of the present preferredembodiment, a magnetic head having a conventional structure in which theposition where the upper magnetic core spreads is located at theposition shown in FIG. 1A and FIG. 1B was manufactured in accordancewith the manufacturing method described with reference to FIG. 3. Thesize of the upper track was measured from the air bearing surface forall the elements and the variation 3 σ in measurements was 0.35 to 0.45μm. In the case of this conventional structure, the variation in thesize of track was large and hence this conventional structure cannotrealize a head for high recording density.

Next, one preferred embodiment of a magnetic disc device using themagnetic head in accordance with the present invention will bedescribed.

FIG. 4 is a schematic perspective view showing one preferred embodimentof a magnetic disc device provided with the magnetic head in accordancewith the present invention. As shown in FIG. 4, the magnetic disc devicecomprises a plurality of magnetic discs 13 stacked at equal intervals ona spindle 38, a magnetic head 15 held by a rotary carriage assembly 14,a voice coil motor 16 for driving the carriage assembly 14, and a base17 for supporting these members. Further, the magnetic disc device isprovided with a voice coil motor control circuit for controlling thevoice coil motor 16 and a control means for controlling a drive motorrotating the magnetic discs 13 (both of them are not shown in FIG. 4)according to a signal from a higher level system such as a magnetic disccontrol system and is connected to the higher level system via aninterface unit for exchanging signals with the higher level system and aread/write circuit for controlling a current passed through the magnetichead. In this respect, the employment of the thin-film magnetic head ofthe preferred embodiment described above as the magnetic head 15 canimprove the reliability of the magnetic disc device and the assemblyyield thereof.

Next, another preferred embodiment will be described with reference toFIG. 5A and FIG. 5B.

FIG. 5A is a plan view of a main part showing another preferredembodiment of the magnetic head in accordance with the presentinvention, and FIG. 5B is a cross sectional view of the main part. Sincethe part of the magnetic head not shown in FIG. 5 is the same as themagnetic head shown in FIG. 2A and FIG. 2B, the part is omitted. Themagnetic head shown in FIG. 5 is different from the magnetic head shownin FIG. 2 in the insulating film determining the zero throat levelposition and the position Pa where the upper magnetic core 10 spreads.

Another preferred embodiment of the magnetic head in accordance with thepresent invention will hereinafter be described with reference to FIG.5. In this magnetic head, the zero throat level position P0 isdetermined by the second layer insulating film 9 a. Therefore, comparedwith the magnetic head of the type determining the zero throat levelposition P0 by the first layer insulating film 7 shown in FIG. 2, themagnetic head of this type can increase the thickness of the insulatingfilm near the zero throat level, that is, the thickness of the secondlayer insulating film 9 a extending in the direction of the air bearingsurface 36 from the tip end of the first layer insulating film 7 and canreduce the possibility of deterioration of magnetic characteristics suchas magnetic flux leak or the like and further can improve the insulatingperformance of the writing element.

Although the insulating film determining the zero throat level is thefirst layer insulating film 7 in the preferred embodiment in FIG. 2, thesecond layer insulating film 9 a determines the zero throat level inanother preferred embodiment in FIG. 5. As shown in FIG. 5A, theposition Pa where the upper magnetic core 10 spreads is located on thesecond layer insulating film 9 a and near to the air bearing surface 36than the tip end of insulating film formed on the second layerinsulating film 9 a and having a level difference thereto, that is, thetip end of the third layer insulating film 9 b.

Next, still another preferred embodiment in accordance with the presentinvention will be described with reference to FIG. 6.

FIG. 6A is a plan view of a main part showing the still anotherpreferred embodiment of the magnetic head in accordance with the presentinvention, and FIG. 6B is a cross sectional view of the main part. Sincethe part of the magnetic head not shown in FIG. 6 is the same as themagnetic head shown in FIG. 2A and FIG. 2B, the part is omitted. Themagnetic head shown in FIG. 6 is different from the magnetic head shownin FIG. 2 in the insulating film determining the zero throat levelposition P0 and in the position Pa where the upper magnetic core 10spreads.

As shown in FIG. 6, in this magnetic head, the position Pa where theupper magnetic core 10 spreads is located near to the air bearingsurface 36 than the tip end of insulating film determining the zerothroat level, that is, the tip end of the second layer insulating film 9a. Therefore, the position Pa where the upper magnetic core 10 spreadsis located between the air bearing surface 36 and the zero throat levelposition P0 and the volume of the upper magnetic core 10 increases fromthis position. This increases magnetic characteristics, in particular,overwriting characteristics.

The magnetic heads of still another preferred embodiment shown in FIG. 6and the magnetic heads of FIG. 5 having the structure in which theposition Pa where the upper magnetic core 10 spreads is located in theback (in the right hand side in the drawing) of the tip end of theinsulating film determining the zero throat level, that is, on thesecond layer insulating film 9 a were manufactured. Then the magneticcharacteristics were measured for the magnetic heads. The test resultsshowed that the magnetic heads of still another preferred embodimentshown in FIG. 6 improved the overwriting characteristics by 30 to 40% onaverage.

In the present invention, the zero throat level position P0 designatesthe tip end of the insulating film extending nearest to the air bearingsurface 36 of the upper magnetic core 10 among the plurality ofinsulating films. That is, the zero throat level position P0 designatesthe tip end of the first layer insulating film 7 in the preferredembodiment in FIG. 2B, and the tip end of the second layer insulatingfilm 9 a in the preferred embodiment in FIG. 5B and FIG. 6B.

As described above, according to the present invention, the magneticcharacteristics and the accuracy of the width of the track of the airbearing surface can be improved by determining the position where theupper magnetic core of the magnetic head spreads.

Further, since the magnetic head according to the present invention hashigh accuracy in the width of the track, it can realize the magneticdisc device with high recording density.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiment is therefore to be considered in all respects asillustrative and not as restrictive, the scope of the present inventionbeing indicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed is:
 1. A recording/reproducing separation type magnetic head comprising: a recording head for recording information to a magnetic recording medium; and, a reproducing head for reproducing information from said magnetic recording medium; wherein said recording head comprises a lower magnetic core, a write gap film on said lower magnetic core for forming a write gap and an upper magnetic core, and said upper magnetic core and said lower magnetic core form a magnetic path by providing said write gap between said upper magnetic core and said lower magnetic core; wherein said upper magnetic core comprises a track portion and a spreading portion spreading from said track portion, wherein a tip end of said track portion of said upper magnetic core constitutes an air bearing surface which faces said magnetic recording medium, wherein a transition between said track portion and said spreading portion is positioned between said air bearing surface and a zero throat level position, wherein said recording head comprises an insulating film provided between said upper magnetic core and said lower magnetic core, wherein said insulating film is formed in multiple layers, and a tip end position of at least one of said multiple insulating layers other than the lowest of said multiple insulating layers extends nearest to said air bearing surface and determines said zero throat level position.
 2. A recording/reproducing separation type magnetic head according to claim 1, wherein said reproducing head is a magnetoresistance effect head having a magnetoresistance effect sensor film.
 3. A recording/reproducing separation type magnetic head according to claim 2, wherein said lower magnetic core is arranged between said upper magnetic core and said reproducing head.
 4. A recording/reproducing separation type magnetic head according to claim 2, wherein said reproducing head comprises an upper shielding film and a lower shielding film arranged with said magnetoresistance-effect sensor film therebetween, and said upper shielding film serves as said lower magnetic core.
 5. A recording/reproducing separation type magnetic head having a recording head for recording information to a magnetic recording medium and a reproducing head for reproducing information from said magnetic recording medium comprising: a lower magnetic core; a write gap film provided on said lower magnetic core for forming a write gap; an upper magnetic core having a track portion and a spreading portion spreading from said track portion, the tip end position of said upper magnetic core constituting an air bearing surface which faces with said magnetic recording medium; insulating films arranged between said lower magnetic core and said upper magnetic core for partly isolating said lower magnetic core from said upper magnetic core more than the thickness of said write gap, wherein said insulating films are formed in multiple layers, and a tip end position of at least one of said multiple insulating layers other than the lowest of said multiple insulating layers extends nearest to said air bearing surface and determines said zero throat level position, and, a coil provided between said insulating films; wherein a transition between said track portion and said spreading portion is positioned between said air bearing surface and a zero throat level position.
 6. A recording/reproducing separation type magnetic head according to claim 5, wherein said reproducing head is a magnetoresistance effect head having a magnetoresistance effect sensor film.
 7. A recording/reproducing separation type magnetic head according to claim 6, wherein said lower magnetic core is arranged between said upper magnetic core and said reproducing head.
 8. A recording/reproducing separation type magnetic head according to claim 6, wherein said reproducing head comprises an upper shielding film and a lower shielding film having said electro resistance effect sensor film therebetween, and said upper shielding film serves as said lower magnetic core.
 9. A recording/reproducing separation type magnetic head comprising: a recording head; and, a reproducing head; said recording head comprising an upper magnetic core, a write gap film on said lower magnetic core for forming a write gap and a lower magnetic core, said upper magnetic core and said lower magnetic core forming a magnetic path including said write gap; wherein said upper magnetic core comprises a track portion and a spreading portion spreading from said track portion, and the tip end position of said upper magnetic core constitutes an air bearing surface which faces with said magnetic recording medium, and the position of said spreading portion of said upper magnetic core is arranged between said zero throat level position and said air bearing surface; wherein said recording head comprises an insulating film provided between said upper magnetic core and said lower magnetic core, wherein said insulating film is formed in multiple layers, and a tip end position of at least one of said multiple insulating layers other than the lowest of said multiple insulating layers extends nearest to said air bearing surface and determines said zero throat level position.
 10. A recording/reproducing separation type magnetic head according to claim 9, wherein said reproducing head is a magnetoresistance effect head having a magnetoresistance effect sensor film.
 11. A recording/reproducing separation type magnetic head according to claim 10, wherein said lower magnetic core is arranged between said upper magnetic core and said reproducing head.
 12. A recording/reproducing separation type magnetic head according to claim 10, wherein said reproducing head comprises an upper shielding film and a lower shielding film having said electro resistance effect sensor film therebetween, and said upper shielding film serves as said lower magnetic core.
 13. A recording head for recording information to a magnetic recording medium comprising: a lower magnetic core; a write gap film provided on said lower magnetic core for forming a write gap; an upper magnetic core having a track portion and a spreading portion spreading from said track portion, the tip end position of said upper magnetic core which constitutes an air bearing surface facing with said magnetic recording medium; an insulating film arranged between said lower magnetic core and said upper magnetic core for partly isolating said lower magnetic core from said upper magnetic core more than the thickness of said write gap; wherein said insulating film is formed in multiple layers and a tip end position of insulating layers among said multiple insulating film layers except the lowest layers is arranged nearest to said air bearing surface, and, a coil provided between said insulating film; wherein a transition between said track portion and said spreading portion is positioned between said air bearing surface and a zero throat level position.
 14. A recording head for recording information to a magnetic recording medium comprising: a lower magnetic core; a write gap film provided on said lower magnetic core for forming a write gap; an upper magnetic core having a track portion and a spreading portion spreading from said track portion, the tip end position of said upper magnetic core which constitutes an air bearing surface facing with said magnetic recording medium; a coil provided between said lower magnetic core and said upper magnetic core; and, an insulating film provided between said lower magnetic core and said upper magnetic core for insulating said coil; wherein said insulating film is formed in multiple layers, and a tip end position of at least one of said multiple insulating layers other than the lowest of said multiple insulating layers extends nearest to said air bearing surface and determines said zero throat level position, wherein the position of said spreading portion of said upper magnetic core is placed at said air bearing surface side than the tip end position of said insulating film layer arranged nearest to said air bearing surface among said multiple layers which separate said upper magnetic core from said lower magnetic core to the upper and lower side than the thickness of said write gap and at rear side than said air bearing surface.
 15. A recording head for recording information to a magnetic recording medium comprising: a lower magnetic core; a write gap film provided on said lower magnetic core for forming a write gap; an upper magnetic core having a track portion and a spreading portion spreading from said track portion, the tip end position of said upper magnetic core which constitutes an air bearing surface facing with said magnetic recording medium; a coil provided between said lower magnetic core and said upper magnetic core; and, a insulating film provided between said lower magnetic core and said upper magnetic core for insulating said coil; wherein said insulating film is formed in multiple layers of insulating films, and a tip end position of said insulating film layers except the lowest layer is arranged nearest to said air bearing surface, wherein a transition between said track portion and said spreading portion is positioned between said air bearing surface and a zero throat level position. 